Vat photopolymerization of Ka-band Luneburg lenses: design, fabrication methods, and characterization

This study investigates the performance of 3D-printed Luneburg lenses using various printable dielectric materials, including commercial resins such as Radix from Rogers Corporation and Rigid 4000 from Formlabs, as well as what we believe to be a new in-house formulated liquid crystal polymer (LCP) resin. Three Luneburg lenses were successfully designed and fabricated using these materials. Step-by-step design processes of 3D printed Luneburg lenses are fully described along with their electrical characterization in the frequency range of 26.5 to 38 GHz. The measurement results reveal that the Luneburg lens fabricated with Radix exhibits the best performance thanks to its low loss. Improvement of gain performance in excess of 14 dB is achieved using a Radix-made in the fabrication process. On the other hand, the Luneburg lens from in-house-formulated LCP demonstrates a similar superior gain improvement up to 13.5 dB. In contrast, the lens fabricated with standard Formlabs resin exhibits inferior performance due to higher loss of the material, which renders it a lower grade candidate for the fabrication of microwave lenses. The paper also offers a comprehensive comparison of the physical properties of the materials in terms of the complexity of the specialized printing process.